Join Order Optimization

regions has 5 rows and customers has 1,000 rows with an index idx_customers_region on region_id. To list the customers of the region named 'EU', the efficient plan is:

1. look at the (tiny) regions table and find EU,
2. use idx_customers_region to fetch only that region's customers.

SQLite normally finds this plan by itself, but in a CROSS JOIN it will never reorder the tables, so you can dictate the loop order yourself.

Write the query with CROSS JOIN so that regions is the outer loop and customers the inner, index-driven loop. Return only the customer name. Do not use table aliases (so the plan text stays readable).

Constraints

• Return one column: the customer name
• Use regions CROSS JOIN customers ON ... (outer loop regions)
• Do not alias the tables
• customers must be searched through idx_customers_region

Hints